My parents have a pond that had been established for about 30yrs, but I had to re-line it this winter. It is about 8000L, and has 9 fish in it which are the offspring of fish which have been there from the beginning. The pond never had a filter, and I’ve been saying for years that it should really have one because of the fish. However, it also has a ton of wildlife. Certainly usually has at least 2 frogs, and we counted 30 newts last year, plus a grass snake. Should I get them a filter when it has been a fish-cum-wildlife pond? I don’t want young newts getting sucked in to the pump, but then again it may take years before the wildlife feel happy again in the pond as it has been disturbed and it would be better for the fish.